Hair generally can be straight, wavy, curly, kinky or twisted. A human hair includes three main morphological components, the cuticle (a thin, outer-most shell of several concentric layers), the cortex (the main body of the hair), and, in case of higher diameter hair, the medulla (a thin, central core). The cuticle and cortex provide the hair strand's mechanical properties, that is, its tendency to have a wave, curl, or kink. A straight hair strand can resemble a rod with a circular cross-section, a wavy hair strand can appear compressed into an oval cross-section, a curly strand can appear further compressed into an elongated ellipse cross-section, and a kinky hair strand cross-section can be flatter still.
The primary component of hair is the cross-linked, alpha-helix protein keratin. Keratins are intermediate filament proteins found specifically in epithelial cells, e.g. human skin and hair, wool, feathers, and nails. The α-helical type I and II keratin intermediate filament proteins (KIFs) with molecular weights around 45-60 kDa are embedded in an amorphous matrix of keratin-associated proteins (KAPs) with molecular weights between 20 to 30 kDa (M. A. Rogers, L. Langbein, S. Praetzel-Wunder, H. Winter, J. Schweizer, J. Int Rev Cytol. 2006; 251:209-6); both intra- and intermolecular disulfide bonds provided by cystines contribute to the cytoskeletal protein network maintaining the cellular scaffolding. In addition to the disulfide cross-links ionic bonding or salt bridges which pair various amino acids found in the hair proteins contribute to the hair strand's outward shape.
It is known in the art that hair can be treated with functionalized silicones which deliver one or more cosmetic benefits, such as conditioning, shine and UV protection as well as color retention. Typically, these silicones are physically deposited on the fiber surface (cuticle) and therefore responsible for the outward appearance of the hair. They can be removed partially or completely by repeated washing processes. While the deposited silicones considerably improve the surface properties of hair, i.e. smoothness and friction, they do not substantially impact the shape, the mechanical properties and the release properties of the hair.
Alternative hair treatment methods are available, but these often involve the use of harsh and regulated substances.
Traditionally, aldehyde based formulations for a permanent hair shaping and hair strengthening were developed. Most frequently formaldehyde is used for this so called Brazilian keratin shaping method (US 2012-0031420). The underlying principle is the crosslinking reaction between formaldehyde and keratin based amino and amido groups (H. Puchtler, Histochemistry, 82(1985), pp. 201-204) or between formaldehyde and —SH groups (US 2009-0211593).
Mixed esters based on glycerol, fatty acids and succinic acid are widely used as emulsifiers in food related applications (JP2017176006, JP2013051916, JP2008011739, JP2006075137, WO2014077385). These mixed esters based on glycerol, fatty acids and succinic acid were also proposed as lubricants (GB635708, DE2904164). They are also known as emulsifiers in cosmetic formulations (CN104069033, WO9410971, EP650717, U.S. Pat. No. 5,489,429, EP2363387). Mixed esters based on glycerol, phthalic or terephthalic acid and succinic acid yield crosslinked polymers for electrical insulations (U.S. Pat. No. 1,098,766, GB1427057).
Surface active esters based on alkyl/alkenylsuccinic acid and glycerol are used as additives for lubricants (FR1370420), in cleaning formulations (SU187917), as rust inhibitors (GB429915) and for textile coatings ((GB766273).
Glycerol 1,2,3-tris(methylsuccinate) is known as an insulin stimulant (L. Ladriere et al, Molecular to Cellular Biochemistry (1999), 198 (1&2), 35-139; L. Ladriere et al, Medical Science Research (1999), 27(5), 303-304; L. Ladriere et al, Molecular Genetics and Metabolism (1999), 67(3), 254-260).
Esters of ethoxylated glycerol and succinic acid are described in GB313892.
Glycerol-succinic acid esters are described in GB755321, GB474630, GB358491. The can be used in photo (GB429915) and agrochemical formulations (JP57154101).
Hyperbranched glycerol-succinic acid copolymers for controlled delivery purposes are also described (T. Zhang et al, Abstracts 44th Central Regional Meeting of the American Chemical Society, Mount Pleasant, Mich., May 15-17 (2013), CERM-6; N. R. Luman et al, Chemistry—A European Journal (2003), 9(22), 5618-5626; G. P. Andrews et al, ACS Symposium Series (2003), 834 8NMR Spectroscopy of Polymers in Solution and in the solid state), 216-227).
Composites using glycerol-succinic acid copolymers as intermediates are described as well (S. Hirose, Pacifichem 2010, Int. Chem Congr. of the Pacific Basin Soc., Honolulu, Hi., December 15-20 (2010), AGRO 56; A. H. Fawcett et al, J. Pol. Sci., Part A: Polymer Chemistry (1994), 32(5), 815-827).
Esters of diacetyltartaric acid with glycerol are known as food additives (WO2017071663, JP2017063619, CN105815536, TW2011143630, JPH07170904).
These diacetyltartaric acid glycerol esters are also known in encapsulations (CN106490571) and in plastisizer formulations (CN104892976).
Mixed esters of tartaric acid with fatty acids and glycerol are also known as food additives (JP2009273441, GB924050, GB1087783, GB881714).
They were also proposed for other applications, i.e. resins (KR20040054557), finishes (JPH04353600, GB388367), alkyd formulations (GB954086, GB498818), lubricants (GB643025), photo (GB577998) and cosmetics (EP2363387).
Tartaric acid glycerol ester were proposed i.e. for resins (GB320041, GB479905), for the modification of fibres (GB497846, GB541047) or as intermediate for emulsifiers (WO2010017651).
Si—O—C linked silicone-amino acid condensates for cosmetic applications are described in J P2001114647 and U.S. Pat. No. 5,854,319.
DE10036522 and DE10036532 describe Si—C— linked amino acid modified silicones. WO2012084826 and U.S. Pat. No. 6,664,342 describe aspartic acid modified silicones.
JP2004269459 describes aspartic acid modified silicone derivatives bearing a cyclic amino acid structure.
There has been a need for efficient compounds for the treatment of fibrous amino acid based substrates, especially hair which can be synthesized in a straight forward and cost efficient way, which are easy to formulate and easy to use, yielding long term stable formulations even in the presence of other performance ingredients and which are useful for strengthening of hair, for hair color retention, for hair color enhancement, hair color deepening, for hair color protection, for shaping of hair, i.e. the curling and straightening of hair, for hair conditioning, for hair smoothening or softening, for hair straightening, and for improving manageability of the hair, in particular for improving the combability of the hair. In particular, benefits regarding the retention of artificial hair colours without the usage of strongly irritating auxiliaries should be achieved.
The present inventors found that new polycarboxylic acid compounds and aqueous compositions comprising the same are suitable to satisfy the above need. The present invention accordingly provides new polycarboxylic acid compounds, aqueous compositions comprising the same, cosmetic compositions comprising the same, in particular, hair care compositions, and their use for the treatment of hair, and a process for the treatment of hair comprising the use of said cosmetic compositions, which polycarboxylic acid compounds can be synthesized in a straightforward and cost-efficient way, are easy to formulate and to use, and are useful for strengthening of hair, for hair color retention, for hair color enhancement, hair color deepening, for hair color protection, for shaping of hair, i.e. the curling and straightening of hair, for hair conditioning, for hair smoothening or softening, for hair straightening, and for improving manageability of the hair, in particular for improving the combability of the hair. In particular, the new polycarboxylic acid compounds and the aqueous compositions comprising the same avoid the usage of strongly irritating auxiliaries.